Expansible and collapsible tap



(No Model.)

I T. F. HAMMER.

EXPANSIBLE AND OOLLAPSIBLE TAP. N0. 397,.1Z6.- Patented Feb. 5, 1889.

5 INVENT'OR:

WITNESSES: a

M m /%W By his Afl01'7zeys,-

7 arts STAT S PATENT rrrcE.

'lHORVAlID l HAMMER, OF BRANFORD, CONNECTICUT.

EXPANSIBLE AND COLLAPSIBLE TAP.

SPECIFICATION forming part of Letters Patent No. 397,126, dated February 5, 1889.

Application filed September 7, 1888. Serial No. 284,817. (No model.)

f0 all whont it 71mg ounce/'71,:

Be it known that l, THORVALD l HAMMER, of Bran ford, New Haven County, Connecticut, have invented certain new and useful Improvements in Expanding and (.ollapsing Taps, of which the following is a specification.

My invention relates to that class of expansible and collapsible taps which are provided with reaming blades or cutters in addition to the threading blades or cutters, so as to ream out the hole to be tapped in advance of the tapping-cutters, and which reamingblades have also an operative connection with the mechanism for expanding and contracting the tapping-cutters, so that the initial torsional or working strain on the reamingcutters when the tap enters the work serves to throw out or expand the tmoping-cutters into their actual position, while the reverse motion or torsion acts to contract the tappingeutters to permit the rapid withdrawal of the tap 011 the back-stroke. Taps of this kind are usually made in large sizes only for use in automatic tapping-machines, and, being subject-ed to great strain, require to possess great strength, stiffness, and endurance to wit-hstand the severe strain and the wear and tear of continual use, and therefore the chief ob ject of my improvements is to produce a co1nbined reaming and threading tap which, with a simple mechanical construction, will possess greatstrength, with ease of operation and power of endurance for constant use.

My improved tap, in its mechanical construction, is more nearly related to that type of tap shown in the expired Patent No. (36,629,015 1867, in which the sustainin shank, stock, orbody of the tool is provided with a series of longitudinal radial slots, in which are socketed a corresponding series of threaded blades or cutters, which may be radially diverged and converged. In the center of the stock is socketed a rotary cam-spindle having a series of cam-faces to bear upon the inner edges of the radial blades, while a cam-ring surrounds the outside of the stock with reverse cam-faces to bear upon the exterior of the blades, said. ring being connected with the central spindle, so that by revolving the ring an d spindle in one direction the blades'are expanded or diverged for tapping, and by turning the ring and spindle in the reverse direction the blades are withdrawn or contracted to permit the quick withdrawal of the tool from the tapped hole. In the former tap, however, as above described, the cutters were made as simple straight radially-slidin g blocks, the movement of the expanding and contracting mechanism was performed solely by hand, and no reamingcutters were provided to ream in advance of the threading-cutters.

Now in my improvements I attach a rosereaming head or disk to the end of the central cam-spindle in advance of the stock and its threading-cutters, so that the initial torsional strain on this reamer as the tool first enters the work acts to automatically operate the cam or expanding mechanism, and thus diverge or expand the threading-blades into position for tapping the hole as fast as reamed by the advancing reamer, while on the reverse mot-ion. of rotation a reverse act-ion will i take place and a spring connected with the cam-ring or other operative part will act to con verge the blades into their retracted position and permit the rapid back motion of the tap. Instead of making the tapping-blades as straight sliding blocks, I form them as tilting or rocking levers, the free or swinging ends of which have the threading or tapping edges, while the opposite or fulcrum end terminates in a fulcrum-tip, which abuts directly upon the body of the stock at the end of the socket-slots, thus forming a fulcrumpoint in a very strong and simple manner without pivot pins or pintles, and without weakening the blades or the stock by pivot holes. I also make the threaded or cutting part of the blade separate from the fulcrum part, so that when worn the threaded or wearable part may be readily removed and a new threaded section attached without requiring to renew the entire blade. I also provide the periphery of the tap-stock at the cutting side of the threading-blades with removable or renewa-ble chip-resisting guards or shields, preferably of hardened steel, which guards receive and deflect the cuttings or chips and prevent rapid or destructive wear of the stock at these points.

My invention therefore consists, mainly, in the features above outlined and in other detail, as hereinafter fully set forth and claimed.

In the drawings, Figure 1 presents a side elevation of my improved tap in its quiescent or collapsed eoinlition, and Fig. 2 an end eleva-tion thereof. Fig. I gives a longitudinal section of the tap in its expanded condition and represented as in action. Fi i is a cross section of the expanded tap on line X. X.

r Fig. is a cross-section on 1 y in the colhtpsed condition. Fig. (5 is a side elevation of a modification, and Fig. 7 a sectional side elevation of another variation.

Referring to Figs. 1, .2, 3, and at, A indicates the stock or body of the tool, which is a strong cylindrical spindle having a contracted shank, a, at one end to enter the chuck or spindle of the tapping-machine in the usual way, while at the opposite end is formed a central bore, 7), which extends into the stock to about one half its length, as shown best in Figs. 3 and 4-. In this central bore is fittedarotarycamspindle, B, having four cam recesses or inclines, 0, corresponding to four radial slots, (I, in the stock, on which are socketed the four threading blades or cutters as clearly shown in Figs. 1, 3, and 4:. In the longitudinal direction the slots 0 do not extend quite.

to the end of the stock, so as to leave the metal continuous at the front end for strength, and they extend backward to about the mid dle of the stock, as seen in Figs. 1 and 3. In radial directions, however, the front portion of the slots extends clear through the stock, or from the periphery into the central bore, as clearly shown in, Figs. and I, while the back portions of the slots are of shallower depth and do not extend into the central bore, thus leaving the metal of the stock continuous at the middle for greater strength and rigidity, as shown at m in Fig. 3. It will also be noted that in my tap, as shown in Fig. 3, the central bore for the cam-spindle does not extend entirely through the stock, and not as far as the radial slots, as the bore terminates at or about the middle of the shallow part of the slots, thus leaving the metal more continuous and solid at the middle of the stock, and thus insuring much greaterstrength and stiffness at an important part of the tool. The tapping-blades C, to correspond with the slots, are made wide at the front or outer ends and narrow at the fulcrum ends, as shown in Fig. 3. The outer edges of the wide ends are serrated or toothed with the section of the desired smew-thread in the manner of a sect-ion of a tap, as usual, as seen in Figs. 1 and 3, while the inner edges are smoothly rounded and engage with the cams c on the cam-spindle 1%, as best seen in Fig. l. The extremity of the narrow part of the blades is formed with a small lulcrumed tip, 6, which rests or abuts directly upon the bearing on or solid part of the stock, which forms the bottom of the narrow part of the slots, as clearly seen in Fig.

Now the exterior of the stock is encircled by a ring, F, which ring is a smooth working lit upon the periphery at or near the middle thereof, and on .its inner edges are formed a series of cam-inclines, f, which are reverse to the inclines of the cam-spindle II, and which bear upon the outer edges of the blades (7, between the fulcrum ends and the threaded parts, as fully shown in Figs. 1, 2, 3, and at. A handle or hand-lever, 1', projects radially from the cam-ring F for manipulation, and a pin, 7., or extension of the handlever projects through a circumferential slot, g, (see Fig. 5,) in the stock and engages the cam-spindle B, thus making a positive rotative connection between the cam-ring and cam-spindle, the slot g permitting a partial rotation of said ring and spindle in either direction equal to the extent of their cams, as will be readily coinprehended from Figs. i and 5.

Referring now to Figs. 1, 2, and 5, which show the tap in its normal or collapsed condition, it will be readily understood that if the handle 1' is moved to the right the canr ring and spindle will be revolved in one direction, and the inclines on the cam-spindle will positively project or diverge the threaded blades (1 into their active position for tapping, as scen in Figs. 3 and 4, while if the handle is moved in the reverse direction the inclines on the cam-ring F will positively retract the blades into their converged or collapsed position, as seen in Figs. 5, f2, and l, the action being substantially the same as in taps of this character heretofore made. In my improved tap, however, while the expanding and mntractingaction maybe performed by hand, as just described, yet an important feature of my improvements consists in the means whereby a reaming blade or cutter on the front end of the tap acts to expand or contract the tapping-cutter automatically that is, referring to 1, 2, and 3, I fix a 'reamer or reaming-disk, G, on the front end of the cam-spindle B in advance of the stock and its threading blades. This reamer is preferably made in the form of a short or flat rose-reamer or ratcllet-reaming disk or mill having a suitable number of properly-formed cutting-teeth around its periphery, as seen in Figs. 2, 3, and l, and this disk rests flat-1y against the front end of the tap-stock, while it has a central square hole which fits upon a short square shank on the end of the camspindle, and is held in place thereon by a "washer, a, and set-screw h, as illustrated in tapping-blades re\"olving, the effect will be to momentarily arrest the reamer and camspindle and cam-ring, while the stock with its threading-blades revolves upon the (3&111-Spl11- dle, and thus causes the cutting-blades to be positively projected into their tapping, position, as seen in Figs. 3 and 5. It will also be seen that when the stock thus turns upon the cam-spindle B and within the cam-ring F, it will compress or wind up the spiral or torsional spring 1), which encircles the stock, with one end secured thereto, while the other end engages the cam-ring, which spring will tend to react to turn the ring in the direct reverse to the advancing rotation, the effect of which will be hereinafter seen. It will be observed that the stock and its blades will continue to revolve in the cam-ring and on the cam spindle (thus projecting the blades and winding the spring) until one side of notches i (see Fig. 2) in the reamingdisk G strikes the stop-pins u u on the end of the stock, which pins limit the motion of the parts when the tapping-blades are proj ected to their proper extent, after which the reamer and the stock, with its projected blades, will all revolve positively together, so as to accurately tap the hole as fast as reamed by the advancing reamer. On the other hand, it will be readily noted that when the rotation of the tool is reversed for withdrawal the reverse action will take place and the cams on the cam-ring F will positively retract the threading-blades into their collapsed position, as seen in Fig. 5, this movement being greatly assisted and rendered much quicker, easier, and more certain by the reaction of the previously-wound spring p, as will be readily understood from the drawings. It is not essential, however, to my invention that the spring p be used to effect or assist the retraction of the blades, as this may be effected by manipulatin g the hand-lever '2' or moving the cam-ring by hand, as before indicated. I greatly, however, prefer to employ the retracting-spring, and do not limit myself to any special manner of applying it to the expanding and contracting mechanism, as it is obvious that it may be applied in various ways and at different points in the train of the expanding and cmtracting mechanism to effect the return movement thereof. Thus, as one instance, Siparate springs p may be applied directly to each blade, as seen in Fig. (5, thereby dispensing with the cam-ring F entirely, which ring may be regarded as a means whereby the power of one spring is applied to all of the blades simultanemisly. It will be seen thatwhere the cam-ring and hand-lever are used without the spring they will form a purely manual device for retracting the blades where the springs p alone in Fig. 6 form a purely automatic retracting device, as does the spring 1) in Fig. 1. Hence while some retracting device acting on the blades reverse to the camspindle B is an essential to my invention, yet l it is immaterial whether this retracting device be purely manual or purely automatic, or embodying bot-l1 the manual and the automatie, as in Fig. 1.

It will be seen that by forming and arrangin g the threading-blades to act as rock-levers, with solid fulcrum-tips abutting directly on the body of the stock at the ends of the slots, the construction is greatly simplified and strengthened, as the use of all pivot-pins or pintles or of pivot-holes in stock or blades are dispensed with, which is a most important advantage in economy and strength. This simple construction is rendered admissible by having the external retracting device (that is, the ring F or the springs 19') bear upon the blades or levers between their fulcrum ends and the ends which rest 011 the camspindle, for in this case it will be noted that the constant tendency of the strains either in expanding or retracting the blades acts to hold the fulcrum end upon their bearings, so that no positive pintle or hinge connection is necessary, as would be otherwise the case.

On referring to Fig. 3 it may be observed that the front or threaded part 4" of the blade is made separate from the narrow or fulcrum part .9, one part having a notch, q, into which a projection, 3 on the other part engages, while the two parts are held securely together by a screw, 2, or other fastening. Hence by this means the threaded and therefore the wearable or destructible part of the blade can be removed and renewed when required without having to renew the entire blade, which is an import-ant provision.

In the operation of large taps of this kind it is found that the chips cut by the tappingblades are projected or curled against the periphery of the stock at the edge of the slots with such force as to rapidly wear the stock and gouge out deep recesses therein after continued use. To prevent this wear, I provide the stock with the chip-resisting guards or shields H, arranged just at the edges of the slots on the cutting side of the blades, as best seen in Figs. 1 and 4, where the said wear or gouging occurs. These guards consist of plates or blocks of hardened steel having dovetailed edges, which slide endwise into dovetailed grooves orsockets cut in the stock close to the side of the slots in which the blades are fitted, as will be clearly understood from Figs. 1 and i, said shields being held in place by the screws] or. other fasteniug.

Instead of making the stock with the elongated slots deep at one end and shallow at the other to inclose the full length of the blades, as in Figs. 1, 2, and (i, the stock may have short deep slots only to receive the threaded partof the blades, as seen in Fig. 7, while the fulcrum part in the blade will lie wholly on the outside of the solid part of the stock, the fulcrum-tips c resting against the shoulder or rim a on the stock and in a l groove, b, turned therein close to the shout der, the construction being otherwise the same as shown in the other figures.

l It will be noted on reference to Fig. 3 that the pins u in the end of the stock engaging the notches t in the ream tug-disk G, form a positive rotative stop or engagement between the reamer and the stock, with a limited play equal to the action of the cams. Such rotative engagement between the stock and the cam mechanism with an idle play equal to the action of the cams is of course essential to the action of the cam mechanism, whereby the independent revolution of the stock and its cutters upon the cam-spindle and iu the cam-ring shall di verge the cutters during the moment that said parts are retarded or arrested by the initial action or engagement of the reamer; but as soon as said indepenct ent rotative play is taken up all parts of the tool will revolve positively together, with the tapping cutters diverged. It will therefore be obvious that this rotative engagement,

with the limited play, might be arranged at any point in the train of the cam mechanismtor example, between the stock and the reamer, between the stock and the camspindle, or between the cam-ring and the stock; but it will be seen that I prefer to place -it directly between the reaming-disk and the stock, which is at the very initial end of the train, and which thus insures greater strength and rigidity and a more positive action, besides being simpler in construct-ion.

What I claim as my invention is 1. In acollapsing tap, the combination, with the sustaining stock or body and radiating movable tapping blades or cutters mounted thereon, and an internal rotary cam-spindle havin camsto bear against and pro j ect the cutters, of a reamer or reaming-head attached to the end of the cam-spindle in advance of the stock and its cutters, whereby the retardation of the advancing reamer in entering the work will cause the cam-spindle to be arrested while the stock and itsblades revolve therein, and thereby automatically expand the tappingcutters, with a retracting device to retract the cutters when the revolution is reversed, substantially as herein set forth.

In a collapsing tap, the combination of the sustaining stock or body having radiallyn'iovable cutters mounted therein, an internal rotary cam-s jiindlc bearing on the cutters, an external ez'nna'ing encircling the stock, connected rotatively with the inner cam-spindle and having inclines bearing externally on the cutters reverse to the inclines ot' the internal cam-spimlle, with a reaming disk or head fixed to the end oi" the cam-spindle, said cam mechanism having a rotative engagement with the stock, with a limited play in the connection equal to the action of the cams, substantially as and for the purpose set forth.

The combination of the stock or body having radially-1novable tapping-cutters, the internal cam-spindle acting to diverge the same, the external cam-ring acting to contract the same, and a retracting'spring tending to turn the ring in its contrary or retracting direction, with a reaming disk or head fixed on the end of the spindle, substantially as and for the purpose set forth.

4. The combination of the stock or body having radially-movable tapping-cutters, the internal cam-spindle acting to diverge the same, and an external retracting device acting to converge the same, with a reaming disk or head fixed on the end of the cam-spindle in advance of the stock and its cutters, and a positive rotative stop or engagement be tween said stock and reamer having a loose rotative play between the two equal to the action of the cams, substantially as and for the purpose set forth.

5. In a collapsing tap, the combination, with a stock or body having radial slots, of movable blades or cutters mounted in said slots and tulcrumed therein by having one extremity abutting directly against and superposed upon the bodyof the stock at the end of the slots, substantially as set forth.

(5. In a collapsing tap, the combination of the slotted stock or body and a series of radially-movable blades or cutters mounted therein, having rocking tulcrnm-tips abutting directly upon a fulcrum seat or bearing in the body of the stock at the ends of the slots, an internal cam or diverging device bearing on the swinging ends of the blades to diverge the same, and an external retracting device bearing on the middle portion of the leverblades between the fulcrum and the swinging or threaded ends, substantially as and for the purpose set forth.

7. In a collapsing tap substantially such set forth, the co1nbination,with the tap-body, of the lever-like threading blades or cutters C, having the fulcrum projection or rocking tip 6 on the extremity opposite to the threaded end, substantially as and for the purpose set forth.

8. The combination of the slotted stock or body A, having the slots (Z made deeply or entirely through the stool: at the front end and partly through the stock at the rear end,- leaving a solid base, m, with the leverlike blades C, fitting said slots and ful crumed therein by having their extremities resting or abutting directly upon the solid base m at the end of said slots, substantially as set to rth.

9. In a collapsing tap, in combination with the tap-Jody, the lever-like threading-blades C, made in two parts, with the threaded parts attachable to and detachable from the fulcrum part, substantially as set forth.

10. In a collapsing tap, in combination with the tap-body, the lever-like threading-blades 0, made in two separate parts, 0* s, with a projection on one part to fit a recess on the other, and a fastening device to hold the two parts together, substantially as set forth.

11. In a collapsing'tap, the combination, with the stock or body having a series of slots and movable cutters set in said slots, of a chip-resisting guard or shield set into the stock at the edge of the slot in the cutting side of the cutters, substantially as and for the purpose set forth.

12. In a collapsing tap, the combination of the stock having longitudinal dovetailed sockets adjoining the tapping blades on. their cutting side, with the hardened blocks H, having dovetailed edges driven into said sockets, substantially as shown and described.

In witness whereof I have hereunto signed IO my name in the presence of two subscribing witnesses.

THORVA'LD F. HAMMER.

Vitnesses:

L. J. NICHOLS, H. E. THATCHER. 

